共查询到20条相似文献，搜索用时 15 毫秒
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Eric Epstein Jaewon Yoon Amit Madhukar K. Jimmy Hsia Paul V. Braun 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(45):6051-6057
The fabrication and properties of pH‐responsive colloidal particles are reported, which change shape rapidly (less than 200 ms), nearly independent of the diffusion of the pH altering species that trigger their actuation, and far more rapid than their Brownian motion. These particles are mechanically bistable, as revealed by their hysteretic shape response. Finite element analysis (FEA) shows that mechanical hysteresis and bistability derives from the colloids' spherical curvature. Mechanical characterization of the bilayered polymers comprising the colloidal particles shows that viscoelastic relaxation plays a non‐negligible role in limiting the shape switching rate; however, energy landscapes obtained from FEA simulations suggest that by tuning the elastic moduli and thicknesses of the constituent polymer layers, microparticles of the size shown here may be fabricated to actuate on timescales as fast as 1 μs. 相似文献
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Paolo Bettotti Cecilia Ada Maestri Romain Guider Ines Mancini Einat Nativ‐Roth Yuval Golan Marina Scarpa 《Advanced Materials Interfaces》2016,3(5)
The design of materials capable of mechanical responses to physical and chemical stimuli represents one of the most exciting and challenging areas of scientific research because of the huge number of their potential applications. This article is focused on the molecular events occurring in thin films of carboxylated nanocellulose fibers, which are capable of converting water gradients into mechanical movements at the macroscopic scale. The analysis of the mechano‐actuation, and of the conditions to obtain it, shows that the film movement is fast and reproducible, the gradient intensity is transduced into rate of displacement, and the response is observed at vapor pressures as low as 1.2 mm Hg. The actuation mechanism is associated to an efficient and reversible water sorption process by the hydrophilic nanocellulose fibers at the film interface. Conversely, water desorption is slow and follows a kinetic behavior supporting the presence of two binding sites for water molecules. The adsorbed water induces swelling of the surface nanocellulose layers and local structural rearrangement, however transitions between ordered and random coil conformations are not observed. The understanding of the actuation mechanisms of nanocellulose offers exciting opportunities to design macroscopic structures responding to chemical gradients by the assembly of simple molecular components. 相似文献
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Dielectric elastomer actuators are stretchable capacitors capable of a musclelike actuation when charged. They will one day be used to replace malfunctioning muscles supposing the driving voltage can be reduced below 24 V. This focus here is on polar dielectric elastomers and their behavior under an electric field. Emphasis is placed on all the features that are correlated with the molecular structure, its synthetic realization, and its impact on properties. Regarding the polymer class, the focus, to some degree, is on polysiloxanes because of their attractively low glass transition temperatures. This enables introduction of highly polar groups to the backbone while maintaining soft elastic properties. The goal is to provide a few guidelines for future research in this emerging field that may be useful for those considering entering this fascinating endeavor. Because of the large number of materials available, a few restrictions in the selection have to be applied. 相似文献
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Jiang Gong Huijuan Lin John W. C. Dunlop Jiayin Yuan 《Advanced materials (Deerfield Beach, Fla.)》2017,29(16)
The first hygroscopically tunable cloth actuator is realized via impregnation of a commercial cloth template by a three dimensionally (3D) nanoporous polymer/carbon nanotube hybrid network. The nanoporous hybrid guarantees diffusion of water into the cloth actuator and amplifies the deformation scale. The cloth actuators are mechanically stable with high tensile strength. Because the commercial cotton cloth is inexpensive, such actuators capable of complex motions can be produced in a large size and scale for a wide variety of utilities (e.g. electric generators and “smart” materials). 相似文献
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Lauren D. Zarzar Philseok Kim Joanna Aizenberg 《Advanced materials (Deerfield Beach, Fla.)》2011,23(12):1419-1419
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Matsuzawa Y Kato H Ohyama H Nishide D Kataura H Yoshida M 《Advanced materials (Deerfield Beach, Fla.)》2011,23(34):3922-3925
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L. Yeghiazarian S. Mahajan C. Montemagno C. Cohen U. Wiesner 《Advanced materials (Deerfield Beach, Fla.)》2005,17(15):1869-1873
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Rong Yin Bao Yang Xujiao Ding Su Liu Wei Zeng Jun Li Su Yang Xiaoming Tao 《Advanced Materials Technologies》2020,5(8)
Soft actuators driven by pneumatic or electric means are heavy and clumsy with physical connections, which hinders their applications in human–machine interactive, wearable, and biomedical fields. Herewith, a light fabric bimorph actuator is reported that is driven wirelessly by optical, thermal, and magnetic energy sources. Being fabricated by laminating electrically conductive fabric and biaxially oriented polypropylene film, the actuators show a large bending curvature of 0.75 cm−1 with optical stimulus and 0.55 cm−1 with magnetic stimulus, a response time of 0.27 s with a bending angle of 100° to magnetic stimulus, more than twice faster than previously reported bimorph actuators. Their remarkable performance is attributed to the optimal structural design based on a verified Timoshenko model, electrothermal and optical properties of the conductive fabric coated by copper/nickel. It is greatly enhanced by the large difference of thermal expansion coefficients between the film and fabric. Various wireless controlled prototypes are demonstrated, including a soft gripper, soft kickers, and artificial blooming flowers, illustrating a new way to mass produce cost‐effective bimorph actuators via a simple, green, and fast approach for applications in robots, wearable, and functional textiles. 相似文献
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Blinco JP Trouillet V Bruns M Gerstel P Gliemann H Barner-Kowollik C 《Advanced materials (Deerfield Beach, Fla.)》2011,23(38):4435-4439